Indoor air - Determination of total organic volatile organic compounds (TVOC) - Gas chromatograph
The determination of TVOC complies with Appendix E of GB 50325-2001 "Test Method for Total Volatile Organic Compounds (TVOC) in Indoor Air". Its principle is to select a suitable adsorbent (Tenax GC or Tenax TA), collect a certain volume of air sample using an adsorption tube, retain the volatile organic compounds in the air flow in the adsorption tube, and after sampling, heat the adsorption tube to desorb the volatile organic compounds. The sample to be tested enters the capillary gas chromatograph with inert carrier gas, and is qualitatively determined by retention time and quantitatively determined by peak height or peak area.
1、 Abstract: A certain volume of air sample is collected using a Tenax TA adsorption tube, and volatile organic compounds in the air are retained in the adsorption tube. The desorption gas of volatile organic compounds is obtained by heating the adsorption tube through a thermal desorption device, and it is injected into a gas chromatograph for chromatographic analysis to determine the retention time and peak area quantitatively.
2、 Detection index: TVOC
3、 Instrument preparation:
1. Thermal desorption device: temperature controllable, gas flow rate adjustable, with six way valve and quantitative tube
2. Gas chromatograph GC-9280: equipped with a hydrogen flame ionization detector, with high sensitivity
3. Special capillary chromatography column: weak polarity, 50m * 0.32mm * 1.0um
4. Standards: Standard solutions of benzene, toluene, p-xylene, o-xylene, styrene, ethylbenzene, butyl acetate, and undecane
5. Dual channel atmospheric sampler: The flow rate is stable during the sampling process, and the flow range includes 0.5 L/min
6. Sampling adsorption tube: A glass tube containing 200mg of Tenax TA adsorbent with a particle size of 0.18mm~0.25mm (60-80 mesh) or a stainless steel tube with a smooth inner wall should be activated by heating with nitrogen gas before use. The activation temperature should be higher than the desorption temperature, and the activation time should not be less than 30min. The activation should be until there are no impurity peaks; Analysis temperature 300 ℃
7. Dual channel chromatography workstation: One workstation can connect two chromatographs
8. Gas source: nitrogen cylinder, hydrogen generator, air generator
4、 Instrument Introduction
GC-9280 gas chromatograph
The GC-9280 gas chromatograph touch screen is a laboratory specific gas chromatograph developed by Prey Instruments. It adopts a 7-inch color touch control and a professional chromatograph UI operation interface design, which intuitively reflects the internal temperature values of the injection port, column temperature box, detector, and the values of each detector, as well as the running time. It has a one click cooling function, making the operation simple and intuitive, and easy to use.
This instrument is widely used in various fields such as scientific research and education, petroleum, chemical engineering, biochemistry, food safety, medicine and health, environmental monitoring, judicial investigation, etc. The instrument has high testing accuracy, good repeatability, and is trustworthy.
Performance characteristics
Injection port flow rate, chromatographic column carrier gas flow rate, detector gas flow rate, precision control
Multiple injection ports can be equipped: filling column injection port (with a spacer for purging, which can be connected to a large-diameter capillary column)
